1. Field of the Invention
The present invention relates to a novel physiologically active substance. A novel physiologically active substance is preferably derived from propolis, has excellent antitumor activity and is useful as an antitumor drug.
2. Prior Art
Propolis is a kind of glue in which resins collected by honeybees are mixed with saliva secretion, beewax, pollen, etc., and known as a folk medicine having a variety of pharmacological activities including anti-microbial activity and anti-inflammatory activity.
It is known that an ethanol extract of propolis has antitumor activity [Z. Naturforsch, C 44. 1063, (1989)].
Further, it is known that phenetyl cafeate, one component of propolis, represented by the formula (II), ##STR2## has antitumor activity [Experientia 44, 230, (1988)].
The process for preparing a propolis extract having antitumor activity has been disclosed by the present inventors (JP,A Hei 3-162596).
Further, as a compound having a skeleton similar to that of the compound of the present invention, compounds represented by the following formulae are known.
Bolivianol represented by the formula (III) [Bol. Soc. Chil, Quim., 35, 257, (1990) (Chemical Abstract 114, 39206u)]. ##STR3##
A compound represented by the formula (IV), ##STR4## (wherein each of X and Y represents CH.sub.2 OH or each of X and Y, independently of other, represents CH.sub.2 OH or H) [Phytochemistry 28, 531, 3415 (1989)].
A compound represented by the formula (V), ##STR5## [Phytochemistry 28, 3415, 2507 (1989)].
A compound represented by the formula (VI), ##STR6## [Phytochemistry 20, 1657 (1981)].
However, there is no report on the antitumor activity of these compounds.